1. Field of the Invention
The invention relates to a setting gauge for setting a depth stop on a handpiece for medical purposes, in particular a handpiece for treating a root canal in a tooth.
2. Description of the Related Art
An above-mentioned handpiece serves, with a tool at its forward end that is effective to remove material, to produce or to prepare drilled holes or cavities in a body, whereby the body may be a part of a human or animal body, or a model for the human or animal body. In the first mentioned case, the handpiece is a medical or dental handpiece. In the second case, there is involved a handpiece for a medical, in particular dental, laboratory in which models or prostheses for parts for a human or animal body, e.g. dental prostheses, are produced.
In many treatment procedures with a handpiece of the present kind, it is of significance that a particular depth of a drilled hole or a cavity is not exceeded, in order e.g. not to penetrate through the wall of the body containing the drilled hole or the cavity. The present problem is of significance in particular in the preparation of root canals in teeth. On the one hand it is possible that a root canal is very strongly curved; that is, that an associated root canal tool does not follow the curvature and therefore requires a restriction of the working depth, so that the root canal tool does not penetrate through the wall of the root canal. A comparable problematic situation arises in the preparation of a conventional root canal which is to be worked with an associated root canal tool up to the so-called apex, whereby however the root canal tool should not be pushed in beyond the apex, since on the one hand this is painful for the patient and on the other hand adversely affects the jaw.
With a known procedure, the depth of the cavity of the drilled hole, or of the root canal, is determined e.g. with the aid of an X-ray image, and a depth stop arranged on the handpiece is so set that it bears against the body to be worked when the tool has reached its maximum working in depth. For the purpose of setting the depth stop on the handpiece there have already been developed setting gauges of various configurations. In accordance with one proposal, the setting gauge is formed by means of a rod-shaped measurement or setting body, on the peripheral surface of which there is provided an axially extending scale. With this setting gauge, a depth stop on the handpiece can be set or checked, in the presence of the tool mounted in the handpiece, in that the setting gauge with its stop surface is manually so applied in the axial direction of the tool or of the scale to the depth stop of the handpiece, and thereby manually held, that the tool extends parallel to the scale, so that its length can be read by means of the comparison of the tool tip with the measuring rod, and can be set by means of an alteration of the depth stop. In the employment of this setting gauge, handling is difficult because both the handpiece and the setting gauge are to be manually held and moved with respect to one another, which is not simple, whereby furthermore a manual alteration of the depth stop is to be effected, which even with the use of two hands of the operating person is difficult.
The object of the invention is to so configure a setting gauge of the kind concerned that a checking or setting of the depth stop can be effected with slight manual effort and more simply.
This object is achieved, according to one aspect of the invention, by means of a handpiece in which a driven end of a tool can be releasably attached so as to extend along an axis to a working end thereof, a stop device mounted on the handpiece for adjustable movement in a direction parallel to the axis and a setting gauge configured to bear against a reference surface on the handpiece and to be removable therefrom and having measures arranged thereon to indicate the position of the stop device along the axis.
According to other aspects, the invention involves a novel setting gauge for setting a moveable depth stop on a handpiece which has a connection device for the releasable connection of a pin-shaped tool for working of a root canal in a tooth, wherein the tool extends in the direction of movement of the depth stop. This novel setting gauge comprises a surface which is bearable against a corresponding surface of the handpiece, a mounting means for mounting the setting gauge on the handpiece to extend parallel to the depth stop, with the bearing surface bearing against a corresponding surface of the handpiece, and at least one scale having markings which represent increasing values in a direction toward s an end of the gauge which corresponds to the handpiece when the gauge is mounted thereon. In one of these other aspects the scale values correspond to the length of the tool which project beyond the depth stop. In another of these other aspects, further scales are provided which have markings corresponding to the lengths of other tools which project beyond the depth stop, those other tools being of different lengths. Advantageous further developments of the invention are described and claimed herein.
The setting gauge in accordance with the invention according to a particular aspect of the invention has a connection element for connecting and positioning the setting gauge on the handpiece in its functional disposition, in which the depth stop can be set on the scale. By this means, the setting gauge can be held on the handpiece so that no special manual grasping and holding of the setting gauge is needed; it can be held together with the handpiece in one hand or can be used in a disposition with the handpiece laid on a supporting surface. Further, in the disposition mounted on the handpiece, the scale on the base body is located in the vicinity of the depth stop, so that this can e.g. be set or pushed out or pushed in, in simple manner with sufficient exactitude.
The configuration according to the invention in accordance with a further aspect of the invention makes possible a setting of the penetration depth of the tool without consideration of the position of the tool or a tip, whereby the depth stop can be set directly on the scale. It is thus not necessary to connect the tool with the handpiece before the setting of the depth. The tool can also be connected with the handpiece after the setting of the depth. By this means, the setting gauge can be positioned on the handpiece more simply and more readily, whereby sufficient space for the setting gauge is also present since the space that the tool would occupy in the vicinity of the depth stop can be taken up by the setting gauge. By these means, a substantial simplification of the manipulation and setting of the depth stop is attained.
Within the scope of the invention it is possible, for determining the scale value which is to be set, to employ an assisting tool with which at least a part of the depth of the cavity to be worked, or of the root canal to be worked, can be measured and transferred to the scale. Thereby, the entire depth does not need to be measured; rather, it is also possible that only a part of the depth is measured, whereby the remaining depth can be determined in another manner, e.g. by means of an X-ray image. These steps lead to the advantage that depths which develop in a curved manner, as is often the case with a root canal, can be more exactly determined.
With both configurations in accordance with the invention it is advantageous to arrange on the base body of the setting gauge a plurality of scales neighbouring one another, which are each associated with a particular tool length. Thereby, the setting of the depth stop is to be carried out on the scale which corresponds to the length of the tool located in the handpiece. In each case the scales are correspondingly positioned and distributed on the base body.
The setting and reading of the scale or scales is simple and reliable, in particular if the at least one scale is formed as a measure and is in particular provided with numbering, whereby the scale may have mm divisions formed by marks, at steps of 1 or 1.5 mm.
In its more specific aspects, the invention leads to simple and economically manufacturable configurations of compact construction, which can be manually handled simply and further improve the visual observation and the handling and holding of the setting gauge on the handpiece.